Used 804 N or S vs New CM10 S2?

"but the tweeters are very different."

With B&W, the tweeters always seem to be the problem. If you can't get a really good, firsthand demo, I would pass.It's just too risky.

What will you use to drive these?

FWIW, I used to have the older CM4 powered by Rotel RB1080 (200W). I upgraded to 804S and suddendly the treble was brittle. It was the more revealing speaker now allowing me to hear the amp's limitations. I upgraded the amp to McIntosh MC275 (tubes), after listening in the same system the 804S with MC275 and MC252 (solid state). Both sounded great, but I liked the tubes better.

Can't talk about the 804N. Never heard them. The 804S are very good when paired with the right equipment, like any other speaker.

What's driving them? Well, I'm really only getting started with this "hobby" so what I have currently is a new Marantz 5009 and I'm using the pre outs going to an Adcom GFA 555II, but I just purchased tonight (from here), a Rotel 1090 (380W/channel) amp that will be here shortly and that is what will be driving them for the time being as I move through the chain and upgrade/add pieces. I had CM10's hooked up to the Adcom and it really didn't sound like it had enough reserve power when played at higher volumes. It was also a little bright/harsh when compared to just playing through the Marantz so it seemed like a good idea to move up a step with the amplifier. This appears to be something that will turn into a long term deal with me and I just can't throw tons of money at it all at once so I'll be putting it together in steps. I've listened t the 804 Diamonds side by side with the CM10's and the are certainly better - a little tighter base, slightly better imaging and more revealing highs than the CM10's) but not in my budget and probably won't be for a year or so at least...

I currently have a pair of 685's and 683's up for sale here. The CM10's I had for a couple of weeks here at my home were worlds better than the 683's. Having heard better speakers in my home, I honestly can't keep the 683's so I have to get something I like more...hence the question and the upgrade path I'm looking for!

Thanks for the replies,

Keep in mind I haven't heard the CM10 so what follows is a bit of a guess.
Considering:
- the new power amp is a Rotel RB1090, which is better than the RB1080 I had yet probably not in a different league,
- the RB1080 plus 804S sounded harsh to me (which you may or may not share),
- the old CM4 and RB1080 didn't bother me,
- you don't want to be spending more money in the coming months

I'm inclined to suggest you drop the 804S off your list. It's a bit counterintuitive suggesting this as I tend to think priority should be placed on better speakers. But this can also lead to insatisfaction with the rest of the chain. That would be your judgement call.

As for CM10 vs. 804N, I can't really offer much insight as I haven't heard either one.

What kind of music do you listen to?
What source/s do you use?

Don't rush it. Well, at least to me the learning involved in each upgrade has been part of the enjoyment.